U2606 – CAN Bus Communication Fault

The ODBII code U2606: CAN Bus Communication Fault indicates a malfunction in the Controller Area Network (CAN) communication system, which may involve issues with data transmission between various vehicle modules.

The severity of ODBII code **U2606: CAN Bus Communication Fault** is generally considered moderate to severe.

Common Causes For: U2603: CAN Bus Communication Error

• Faulty CAN bus wiring or connectors
• Short circuit in the CAN bus
• Open circuit in the CAN bus
• Faulty or malfunctioning ECU (Electronic Control Unit)
• Interference from other electrical components
• Corroded or damaged connectors
• Poor ground connections
• Faulty CAN bus transceiver
• Software issues or bugs in the ECU
• Incompatible aftermarket components or modifications

Common misdiagnosis for U2606: CAN Bus Communication Fault

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Bad wiring or connectors
• Faulty sensors
• Powertrain Control Module (PCM) issues
• Battery or charging system problems
• Grounding issues
• Faulty CAN Bus transceiver
• Software or firmware issues
• Intermittent electrical connections

Common Troubleshooting Steps

The OBD-II code **U2606: CAN Bus Communication Fault** indicates a communication issue on the Controller Area Network (CAN) bus, which is responsible for allowing various vehicle control modules to communicate with each other. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Other codes may provide more context or indicate which module is having issues.
• Inspect Wiring and Connectors:
• Visually inspect the wiring and connectors associated with the CAN bus. Look for damaged, frayed, or corroded wires and loose or corroded connectors.
• Pay special attention to the connectors on the modules that are part of the CAN network.
• Check for Short Circuits:
• Use a multimeter to check for short circuits between the CAN high (usually a green wire) and CAN low (usually a yellow wire) lines.
• Ensure that there are no shorts to ground or power.
• Test the CAN Bus Voltage:
• Measure the voltage on the CAN high and CAN low lines with the ignition on (engine off). The typical voltage levels should be around 2.5V to 2.8V for both lines.
• If the voltage is significantly off, it may indicate a problem with the bus or a module.
• Check Termination Resistors:
• Ensure that the CAN bus has the correct termination resistors (typically 120 ohms) at both ends of the bus. A missing or faulty resistor can cause communication issues.
• Inspect Modules:
• Identify which modules are connected to the CAN bus and check for any signs of failure. A malfunctioning module can disrupt communication.
• If possible, disconnect modules one at a time to see if the code clears or if communication is restored.
• Scan for Module Communication:
• Use a scan tool to check if all modules on the CAN bus are communicating properly. Some advanced scan tools can perform a network test to identify communication issues.
• Check for Interference:
• Look for any aftermarket devices or modifications that may interfere with the CAN bus communication, such as alarms, remote starters, or audio systems.
• Update or Reprogram Modules:
• In some cases, updating or reprogramming the affected modules may resolve communication issues. Check with the manufacturer for any available updates.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have identified common issues and provided solutions. 1
• Professional Diagnosis:
• If the issue persists after performing these steps, consider seeking help from a professional mechanic or dealership with experience in diagnosing CAN bus issues. By following these steps, you should be able to identify and resolve the cause of the U2606 code.